Ship stabilizer



Oct; 31, 1967 s. B. F11-:LD ETAL SHIP STABILIZER 5 Sheets-Sheet l FiledAug. 24, 1965 OC- 31, 1957 s. B. FIELD ETAL 3,349,743

SHIP STABILIZER Filed Aug. 24, 1965 5 sheets-sheet 2 INVENTORS ATORNEYS.

UCL 3.1, 1967 s. B. FIELD ETAL. 3,349,743

SHIP STABILIZER Filed Aug. 24, 1965 5 Sheets-Sheet 5 nimm ATTORNEYSUnited States Patent O 3,349,743 SHIP STABILIZER Sheldon B. Field,-Floral Park, and Thomas F. Bridges,

Port Washington, N.Y., assignors to John J. McMullen Associates, Inc.,New York, N.Y., a corporation of New York Filed Aug. 24, 1965, Ser. No.482,059 2 Claims. (Cl. 114-125) ABSTRACT F THE DISCLOSURE A bulk carriervessel having a passive free surface tank stabilizer formed by theexisting ship structure and comprising a pair of wing tanks located justbeneath the main deck along the upper outboard sides of the hull andbeing elongated in the longitudinal direction and each having an`inboard side formed by a downward and outward extending plate whichserves to house tank liquid and reinforce the main deck. A perforatedbulkhead is provided in each wing tank and arranged in the athwartshipdirection to minimize the fore and aft swash of the tank liquid.Existing girder plates project upward and outward from a bottom platemounted on top of a corrugated bulkhead to transmit supporting forces tothe main deck and serve as an interconnecting channel with a truncatedprole for the wing tanks. The wing tank fore and aft dimension isgreater than the channel so as to form a C-shaped tank. An apertureplate is secured to the boundary of the channel and wing tank and slopesdownward and outward from the top of the tank and provides hydrodynamicdamping for the liquid lbody which partially fills the tank.

The present invention provides a ship stabilizer and more particularly astabilizer made mostly of existing ship structure such as the deck andsupporting girder plates conventionally found in bulk cargo ships andthe like.

The use of water tanks for the purpose of roll stabilizing a vesseldates back to the early 1900s and Frahms early contribution to the art.See U.S. Patent No. 970,368. How-` ever, the industry did not considerthe use of water tanks commercially feasible until the recentdevelopment of the flume type stabilizer; see, for example, U.S. PatentNo. 3,054,373. Now that roll stabilization systems are being widelyused, there is a present need in the art to reduce the expense, weightand volume requirements thereof so that the stabilizers detract `aslittle as possible from the cargo handling capabilities of the vesselwithout losing their stabilizing effectiveness.

One concept of reducing the space and weight needed for stabilizers isto use existing ship structure as the container and damping means forthe liquid stabilizing medium. But to use existing ship members as partof the stabilization system creates stress problems which must be solvedso that the strength and structural function of these members are notundermined. One such solution is disclosed in U.S. Patent No. 3,164,120,wherein the stabilization system for a liquid cargo tanker comprises theexisting longitudinal and transverse structural bulkhead system whichcooperates with a portion of the hull.

But the problem of using existing ship structure for the stabilizationsystem in a bulk cargo vessel still exists. Therefore, it is a primaryobject of the present invention to provide a stabilization system for abulk cargo vessel wherein said system comprises, at least in part,existing structural members normally found in vessels of this type.

It is another object of the present invention to use existing structuralelements of a bulk cargo vessel as part of the stabilization systemtherefor, without undermining or detracting from the structuralfunctions of these elements.

ICC

It is yet a further object of the present invention to provide a shipstabilizer which in part comprises the supporting deck girders normallyfound in bulk cargo vessels.

It is still a further object of the present invention to provide aplurality of stabilizing containers spaced throughout the length of thevessel.

Other and further objects of the present invention will become apparentwith the following detailed description when taken in view of theappended drawings in which:

FIG. 1 is a side elevation of a vessel schematically illustrating thepositions of the stabilizer tanks in relation to the holes, corrugatedtransverse bulkheads, and deck;

FIG. 2 is a side sectional view taken along line 2--2 of FIG. 1;

FIG. 3 is a side sectional view taken along line 3-34 of FIG. l;

FIG. 4 is a developed fragmentary view of the restricting plate takenalong line 4 4 of FIG. 2;

FIG. 5 is a sectional elevation view taken along line 5-5 of FIG. 3; and

FIG. 6 is a sectional elevation view of the Wing tank taken along line 66 of FIG. 5.

Referring to the drawings in detail, there is illustrated in FIG. l aconventional bulk carrying cargo ship, generally indicated as 10, havinga plurality of longitudinally spaced holds 12 separated by corrugatedtransverse bulkheads 14 and provided with a main or upper deck 16. Asuitable number of longitudinal bulkheads 18 extend substantiallythroughout the length of the ship and divide holds 12 into a number oflateral compartments. Each hold 12 has one or more hatchways 20 throughwhich bulk cargo material is loaded and unloaded. Sloping, elongatedgirder plates 22 are positioned across the hull, and each has one edgein supporting engagement with the underside of main deck 16 and itsother edge rigidly mounted to the top of corrugated transverse bulkheads14. Any suitable manner, such as welding and the like, can be used tosecure these edges to deck 16 and the supporting struc,- ture. Forincreased structural support, the girder plates 22 and their associateddeck portion form in cross section a rigid triangular structure, betterseen in FIG. 5.

An elongated narrow plate 24 is mounted atop each corrugated bulkhead 14and serves as a -base or bottom to which the lower sides of plates 22are secured.

In accordance with the present invention, a pair of wing tanks 30 are'built in next to the hull just below deck 16 and serve as part of thestabilization system in cooperation with selected pairs of the girderplates 22. Thesegirder plates form the sides of the crossover channelbetween wing tanks 30 as further described below.

Referring to FIGS. 26, each wing tank 30 has two liquid-tight bulkheads32 and a sloping bottom plate 34 which has a vertical leg 36 and ahorizontal leg 38 welded to deck 16 and the hull, respectively. Avertically mounted transverse web 40 is mounted in each wing tank withits edges entirely in contact with plate 34, a portion of the hull, anda portion of the main deck 16. Web 40 serves to add additionaltransverse rigidity to the ship.

As can be seen in FIGS. 2-5, the portion of plate 34 mounted across thearea at which the space between girder plates 22 communicates with therespective wing tank 30 serves as a sloping restriction plate 42. Aplurality of restrictions or cuts 44 is provided therein and theseopenings decrease in dimension and cross section as they approach thebottom of plate 42 so as to interfere as little as possible with theforce distribution within plate 42. Plate 42 terminates in an uppervertical leg 46, the top of which is welded or otherwise secured to theunderside of main deck 16, and openings 48 are provided therein toreduce weight and to enable a free passage of air in a manner describedbelow. A swash bulkhead 50 is provided in each wing tank, preferablynear the center thereof in order to prevent local sway and to eliminateunwanted turbulence from the wing tank.

The operation of the present invention will now be described. It isreadily understood that the sloping deck girders 22 function in theirnormal manner to give the required structural support to main deck 16,and that the space between girders 22 provides a connecting channelbetween the pair of transversely aligned wing tanks 30 located atopposite sides of the hull. Additional structural support and rigidityis afforded by transverse webs 40 and liquid-tight bulkheads 32. Inaddition, girders 22 and bulkheads 32, along with bottom plates 34, maindeck 16 and the hull of vessel 10, define an elongated, enclosed liquidcontainer or tank which, when filled with a body of liquid, serves asthe passive stabilization system for vessel 10. As the ship 10experiences roll in response to the action of the particular sea, theliquid within the stabilizer transfers from one side to the other inresponse to the roll, and the effective mass of the liquid shifts toimpart a stabilization moment to the vessel. Restriction plates 42provide the appropriate energy dissipation and liquid damping as theliquid transfers therethrough.

The air above the liquid surface transfers freely between the wing tanks30 and the connecting channel through vopenings 46 or any uncovered cuts44 in restricting plate 42. This transfer of liquid from one side of thestabilizer to the other continues as long as the vessel continues toroll.

Any suitable liquid such as fuel, bunker oil, sea water and the like canbe used as the stabilizing medium within the stabilizer. The naturalfrequency of liquid oscillation within the stabilizer can be selected tomatch the particular conditions of the ship and sea by merely adjustingthe height of the liquid within the stabilizer. To develop the propermoment magnitude', a predetermined plurality of stabilizers are built ininto the vessel and can be partially filled with liquid to operate inthe marmer described.

Other and further modifications can be made to the present inventionwithout departing from the spirit and scope thereof, and it should beunderstood that although only two stabilizer locations were shown, anynumber of stabilizers can be used in order to obtain the desiredmagnitude of stabilizing moment required for a particular vessel. Itshould further be understood that although the plan profile of thecontainer is shown as being C-shaped (see FIG. 3), plan containerprofiles of Z-shape and H- shape are also within the scope of thepresent invention.

What is claimed is:

1. A bulk carrier vessel having a main deck and a hull and a passivestabilizer tank extending across said hull, comprising a pair of wingtanks each located beneath said main deck at an upper outboard side ofthe hull and having its inboard bottom wall formed by a downward andoutward sloping plate having its top secured to the main deck undersurface and its outboard edge secured to the respective hull side, saidtank further including an interconnecting channel formed -by a bottomplate extending the length of the tank, a pair of girder platesprojecting upward and fore and aft respectively from said bottom plateand having their top edges secured to the under surface of said maindeck so as to transmit supporting forces thereto, said girder platesextending athwartship and intersecting the inboard walls of the wingtank so that the interconnecting channel has a truncated profile incross section, the fore and aft dimension of the interconnecting channelbeing less than the fore and aft dimensions of said wing tanks so as toform a C-shaped tank, each said plate forming inboard side of each wingtank defining a plurality of openings aligned with the profile of theinterconnecting channel to permit substantial liquid passage into andout of the wing tanks during the roll cycle and to provide a suitableamount of damping thereto, said openings extending in zones fromgenerally the bottom to the top of the tank for hydrodynamically dampingthe liquid passage but permitting a free transfer of air therethrough,and a swash bulkhead arranged transversely in each wing tank andprovided with a plurality of openings so as to decrease the fore and aftswash movement of liquid therein during operation, and a body of liquidpartially filling the tank so as to form an air space over all partsthereof in the interconnecting channel and the wing tank, the liquidlevel being such that the tank liquid oscillation is generally tuned tothe ships roll, said vessel further comprising a corrugated transversebulkhead secured therein contributing to the primary support for themain deck and having its top supporting said bottom plate of said tankso as to counteract the loading forces through the girder plates.

2. A vessel as set forth in claim 1 wherein the plates forming theinboard sides of each wing tank comprise an inboard vertical sectionconnected to the main deck and an outboard horizontal section connectedto the hull.

References Cited UNITED STATES PATENTS 932,722 8/1909 Simpson 114-125986,861 3/1911 Reid 114-4125 3,054,373 9/1962 Ripley 114-125 3,228,3681/1966 Deal et al 114-125 MILTON BUCHLER, Primary Examiner.

T. M. BLIX, Assistant Examiner.

1. A BULK CARRIER VESSEL HAVING A MAIN DECK AND A HULL AND A PASSIVESTABILIZER TANK EXTENDING ACROSS SAID HULL, COMPRISING A PAIR OF WINGTANK EACH LOCATED BENEATH SAID MAIN DECK AT AN UPPER OUTBOARD SIDE OFTHE HULL AND HAVING ITS INBOARD BOTTOM WALL FORMED BY A DOWNWARD ANDOUTWARD SLOPING PLATE HAVING ITS TOP SECURED TO THE MAIN DECK UNDERSURFACE AND ITS OUTBOARD EDGE SECURED TO THE RESPECTIVE HULL SIDE, SAIDTANK FURTHER INCLUDING AN INTERCONNECTING CHANNEL FORMED BY A BOTTOMPLATE EXTENDING THE LENGTH OF THE TANK, A PAIR OF GIRDER PLATESPROJECTING UPWARD AND FORE AND AFT RESPECTIVELY FROM SAID BOTTOM PLATEAND HAVING THEIR TOP EDGES SECURED TO THE UNDER SURFACE OF SAID MAINDECK SO AS TO TRANSMIT SUPPORTING FORCES THERETO, SAID GIRDER PLATESEXTENDING ATHWARTSHIP AND INTERSECTING THE INBOARD WALLS OF THE WINGTANK SO THAT THE INTERCONNECTING CHANNEL HAS A TRUNCATED PROFILE INCROSS SECTION, THE FORE AND AFT DIMENSION OF THE INTERCONNECTING CHANNELBEING LESS THAN THE FORE AND AFT DIMENSIONS OF SAID WING TANKS SO AS TOFORM A C-SHAPED TANK, EACH SAID PLATE FORING INBOARD SIDE OF EACH WINGTANK DEFINING A PLURALITY OF OPENINGS ALIGNED WITH THE PROFILE OF THEINTERCONNECTING CHANNEL TO PERMIT SUBSTANTIAL LIQUID PASSAGE INTO ANDOUT OF THE WING TANKS DURING THE ROLL CYCLE AND TO PROVIDE A SUITABLEAMOUNT OF DAMPING THERETO, SAID OPENINGS EXTENDING IN ZONES FROMGENERALLY THE BOTTOM TO THE TOP OF THE TANK FOR HYDRODYNAMICALLY DAMPINGTHE LIQUID PASSAGE BUT PERMITTING A FREE TRANSFER OF AIR THERETHROUGH,AND A SWASH BULKHEAD ARRANGED TRANSVERSELY IN EACH WING TANK ANDPROVIDED WITH A PLURALITY OF OPENINGS SO AS TO DECREASE THE FORE AND AFTSWASH MOVEMENT OF LIQUID THEREIN DURING OPERATION, AND A BODY OF LIQUIDPARTIALLY FILLING THE TANK SO AS TO FORM AN AIR SPACE OVER ALL PARTSTHEREOF IN THE INTERCONNECTING CHANNEL AND THE WING TANK, THE LIQUIDLEVEL BEING SUCH THAT THE TANK LIQUID OSCILLATION IS GENERALLY TUNED TOTHE SHIP''S ROLL, SAID VESSEL FURTHER COMPRISING A CORRUGATED TRANSVERSEBULKHEAD SECURED THEREIN CONTRIBUTING TO THE PRIMARY SUPPORT FOR THEMAIN DECK AND HAVING ITS TOP SUPPORTING SAID BOTTOM PLATE OF SAID TANKSO AS TO COUNTERACT THE LOADING FORCES THROUGH THE GIRDER PLATES.